Certificate of correction



1962. c. R. WINSTON 3,060,429

METHOD OF AND APPARATUS FOR TRANSFERRING INK Filed May 16, 1958 INVENTORCHARLES R. WINSTON ATTORN Y tinned Patent-p 3,060,429 METHUD 9F ANDAPPARATU FUR TRANSFEERENG ENK Charles R. Winston, Chicago, 1111.,assignor to Teletype Corporation, Chicago, lilh, a corporation ofDelaware Filed May 16, 1958, Ser. No. 735,817 7 Claims. (Ci. Me -1) Thisinvention relates to a method of and apparatus for applying a markingmedium to a recording medium, and more particularly, to an electrostaticinking apparatus and a method for electrostatically depositing ink oncontrolled areas of a receiving surface.

In the past, there have been numerous attempts to effect non-impactprinting by positioning a plate, having conductive character-delineatingelectrodes formed on it, behind sheets of recording media such as paperor like receiving surfaces, and then generating a spray, mist or smokeof marking medium such as a dye or an ink in front of the receivingsurface and attracting the ink to the plate by an electromagnetic orelectrostatic field, thereby to attract particles of ink to the paper orother receiving surface in the areas outlined by thecharacter-delineating portions of the plate. There have also beenattempts to attract a jet of ink to a receiving surface, but suchattempts have not proved to be commercially feasible due to the tendencyof the jet to form into a spray and due to the inability of theprior-known devices to control the jet.

It is an object of the present invention to provide a method of andapparatus for applying a controlled jet of a marking medium to arecording medium.

Another object of the present invention is to provide a method of andapparatus for electrostatically forming a controled ray-like jet of amarking medium and directing it to a receiving surface.

A still further object of the present invention is to provide a methodof and apparatus for forming a controlled jet of ink electrostatically,and for guiding the jet so formed to deflect its course in accordancewith a prede termined pattern.

Yet another object of the invention is to provide a mechanism for and amethod of electrostatically generating a ray-like jet of ink between asource of ink and a receiving surface and for utilizing electrostaticdevices to accelerate the travel of the jet and to deflect the jet inaccordance with a predetermined pattern.

In accordance with one embodiment of the invention, ink is delivered toa capillary nozzle under suflicient pressure to form a bulge or convexmeniscus at the end of the nozzle, but not suflicient to product a flowof the ink out of the nozzle. An electrostatic field is establishedbetween the nozzle and a conductive platen which is placed opposite theexit of the nozzle, by applying a potential difference between theplaten and nozzle, whereby the ink is drawn out and the bulge will bedrawn into an elongated shape having a tip from which a fine ray-likejet is drawn toward the plate or platen. This will result in a jet ofink being directed from the capillary nozzle toward the platen,approximately in a direction normal to the surface of the platen. If asheet of paper or strip of paper or other recording medium is placedagainst the platen, a line may be drawn on the tape or sheet if thesheet is moved along the plate or platen. Interruption of the jet may beeffected by reducing the potential difference between the platen and thenozzle, and consequently, marks of controlled length may be made on thesheet of paper.

While the just described method is the preferred method of maintaining asupply of marking medium at the required distance from the platen, ithas been found that a jet will be drawn from other types of supply meanswhich will so localize the supply that the point from which the jet isdrawn, may be controlled.

In another embodiment of the invention, the method may be practiced byutilizing a valving plate or anode having a hole in its through whichthe jet of ink is directed. By varying the voltage applied to thisvalving plate, the jet may be controlled to interrupt its flow towardthe ink receiving surface and platen. This plate also serves to preventthe jet of ink from forming into a spray and maintains the jet in aray-like stream.

In a still further embodiment of the invention, there are provideddeflecting electrodes for deflecting the direction of the jet by varyingthe voltage applied to the electrodes and these electrodes arecontrolled to cause the jet to form characters or other patterns on atape or sheet may be held stationary against the platen or may be movedcontinuously or step by step along the platen.

A more complete understanding of the invention may be had by referenceto the following detailed description when considered in conjunctionwith the accompanying drawing wherein:

FIG. 1 is an illustration of the simplest form of the apparatus, whereina jet of ink is directed against a paper tape;

FlG. 2 is a fragmentary detailed view showing the capillary nozzle;

FIG. 3 is a diagrammatic view illustrating a second embodiment of theinvention, wherein a valving plate is used for controlling the flow ofthe jet of ink;

FIG. 4 is a diagrammatic view of an alternate embodiment of theinvention utilizing an accelerating plate and a valving plate forcontrolling the fiow of the jet, and

FIG. 5 is a diagrammatic view similar to FIGS. 1, 3 and 4 showing, inaddition to the material shown in FIG. 4, sets of electrodes fordeflecting the ray-like jet or beam of ink from its path to control thedeposition of the ink on the paper in a predetermined pattern which maybe controlled by controlling the voltages supplied to the defleetingelectrodes.

Referring to the drawing wherein like reference numerals designate thesame parts in the several views, particular reference being had to FIG.1, wherein there is illustrated the simplest form of the apparatus forpracticing the invention, it will be seen that there is provided a webor tape 10 of paper or other ink receiving medium. This tape 10 may bemoved across the face of a conductive platen 11 by any suitable drivingmeans and serves as a record strip onto which a stream or jet of ink 12is to be directed from a nozzle 13.

In a form of the invention which has been found to operatesatisfactorily, the nozzle 13 at its exit end comprises a capillary tube14 having an inside diameter of the order of .005 inch and an outsidediameter of the order of .010 inch. This tube 14 may be made ofconducting or non-conducting material. The exit end of the nozzle 13 wasspaced from the platen 11 a distance of approximately .035 inch and thenozzle 13 was supplied with ink from a reservoir 15 under suflicienthydrostatic pressure to cause the ink to form a convex meniscus such asshown at 16 in FIG. 2, but not suflicient to cause the ink to flow fromthe nozzle 13 unless influenced by other forces than the hydrostaticpressure. With a capillary tube 14, having the just-mentioneddimensions, it was found that a proper meniscus 16 was formed if thesurface of the ink in the reservoir 15 was 6 inches above the capillarytube 14. The ink used was a red stamp pad ink manufactured by PhillipsProcess Company, of Rochester, New York, under the trade name ClearPrint.

In this apparatus, since a non-conducting tube 14 was used, an electrode17 was positioned in contact with the ink in the nozzle 13 and connectedthrough a control device 18 to the positive side of a voltage source 1?,the negative side of which was connected to the platen or plate 11. Uponoperation of the control device, a potential difference of approximately1800 volts was applied between the platen 11 and the ink through theelectrode 17. This caused the ink bulge or meniscus 16 at the exit endof the capillary tube 14 to be attracted toward the platen 11 in aray-like jet 12 of minute droplets. The voltage applied between theplate 11 and the ink through the electrode 17 produces a force on thesurface of the ink which is equivalent to a positive pressure tending toextend the bulge at the capillary orifice. This pressure was found to beequivalent to several inches of hydrostatic pressure.

In addition to this electrostatic pressure effect, which is aanlogous tohydrostatic pressure, there is the further effect peculiar toelectrostatics, that the force on any portion of the surface of the inkincreases as that area approaches the platen 11. Thus, there is apressure gradient along the jet 12 of ink which reaches a muimum at thepoint closest to the platen 11. Therefore, the bulge or meniscus 16 ismodified by the application of the voltage between the electrode 17 andplaten 11 and the central portion of the meniscus being originallycloser to the platen 11 will be more strongly attracted toward theplaten 11 than the circumference thereof. This results in the meniscus16 being drawn out into a progressively narrower stream or jet 12 asillustrated in FIG. 2.

Thus, when a voltage is applied between the electrode 17 and the platen11 opposite charges build up on the ink at the nozzle 13 and the platen11. Any one unit charge on the surface of the ink is attracted by everycharge on the platen 11, but the unit charge at the geometric center ofthe ink meniscus, being closer to more charges on the platen than anyother, will be more strongly attracted to the platen 11 and hence willtend to move toward the platen, lifting the ink in its vicinity abovethe surrounding level to form a protuberance. When this occurs, anothereffect takes place. All the like charges on the surface of the ink repeleach other and will therefore tend to push an excess of charge to theend of the protuberance. This extra charge is also attracted toward theplaten and therefore increases the force on the protuberance, making itextend even more. The cumulative effect of this action is to form aray-like jet of the ink moving toward the platen. The degree ofextension of the meniscus and drawing out of the ink into the jetdepends upon the surface tension of the liquid (which seeks to minimizethe area of the bulge), the net hydrostatic pressures (which tend toexert a pressure outward in all directions) and on the outside diameterof the capillary tube 14 (which determined the basic size of themeniscus or bulge in the first place). It has been found that the inkwhich enters the meniscus or bulge 16 at the exit end of the capillarytube 14 at a very low velocity will be accelerated along the extendedportion or protrusion and that, due to the increasing velocity of flow,the protrusion will become narrower as it moves out. This narrowingcontinues until some undetermined point at which the protrusion becomesno smaller, but breaks up into droplets which maintain the diameter ofthe stream independently of their velocities and constitute a ray-likejet which has diminished to a diameter order of magnitude less than thediameter of the capillary tube 14 (Le, on the order of one-twentieth toone one-hundredth). It has also been discovered that the stream can bemaintained uniform along its entire length after it has been reduced tothe size of the jet only under proper conditions of the shape of theelectrostatic field and the intensity gradient. Otherwise, because ofdiverging field effects and mutual repulsion of the droplets, a spraywill be formed.

It has also been discovered that, in order to produce a satisfactory jetof ink over a predetermined distance, the applied voltage should bemaintained within predetermined limits. For example, if the end of thecapillary tube 14 and the web supporting surface of the platen 11 arespaced apart .040 to .045 inch and a potential difference of 2000 voltsis applied between the capillary tube 14 and the platen 11, a jet willbe formed substantially conforming to the configuration disclosed inFIG. 2. This jet will start to form when the potential diiference is1800 volts, will completely form when the potential difference reaches2000 volts and will be maintained if the potential difference ismaintained between 2000 and 2200 volts. If the potential differencebetween the nozzle 13 and the platen 11 is increased to 2500 volts,there is a tendency for the meniscus to move back toward the shape shownat 16. However, a jet of ink will still be formed and may be guided bysuitable electrodes at the proper potentials. When the potentialdiflference is raised to approximately 3000 volts, a corona or are isformed and the jet is destroyed. In the just-described procedures thespacing of the nozzle 13 from the platen 11 was .040 to .045 inch.

In arriving at the proper voltages to use in the method of the presentinvention a plate, similar to the platen 11, was spaced from a nozzle,similar to the nozzle 13, a distance of approximately .075 inch, thisplate was covered with a layer of insulation approximately .006

inch thick and a potential difference of 3000 volts was applied betweenthe plate and nozzle. Under these conditions the jet became somewhaterratic and the surface of the bulge or meniscus became somewhat ragged.When the potential diiference, under the just-stated conditions, wasraised to 5000 volts, a series of jets were formed which were separateand the meniscus moved back to a position about flat with the end of thecapillary tube 14-. When the potential difference was raised to 6000volts a corona effect was noted, the jets stopped forming and aspray-like discharge occurred. Upon raising the potential differencebetween the nozzle and plate to 7000 volts, the insulation covering theplate broke down and a spark discharge occurred at the surface of thesupply of ink at the end of the nozzle, disrupting operation.

The ray-like jet of ink is so fine that, while a very fine line of inkon a moving web of paper will be formed when the hydrostatic head of inkat the capillary is maintained as described hereinbefore, it has beenfound that the jet will be forced to carry more ink if the hydrostaticpressure at the nozzle is increased. As a matter of fact, a head ofpressure of 18 inches has produced a highly satisfactory jet even thoughthis high a head of pressure may cause the ink to ooze out of thecapillary tube when no jet is being formed electrostatically.

As soon as the platen 11 and the electrode 17 are restored to the samepotential, the electrostatic effect will disappear and the inkconfiguration will return to that of the slight bulge or meniscus asshown at 16 in FIG. 2. When the potential difference is reapplied, thedynamic configuration will re-appear, but not immediately. There is atime lag of the order of a millisecond or less between the instantvoltage is applied and the instant When the dynamic equilibriumcondition is reached. The time lag is largely a function of theviscosity of the marking medium or ink that is used, and obviously, thetime lag will increase as the viscosity increases. The time lag thuscould decrease if a less viscous ink were used than the ink describedhereinbefore.

From the foregoing, it will be apparent that if the tape 10 is movedacross the platen 11 at a known con stant velocity, a record may be madeupon the tape 10 in the form of a line which will indicate the durationof a pulse sent through the control device 18, to indicate the conditionof the control device 18 in graphic form on the tape.

In the embodiment of the invention disclosed in FIG. 3, the nozzle 13,having ink supplied to it at a pressure sufficient to form the propermeniscus or bulge 16, is

positioned at a distance of .040 to .045 inch from a valving plate 21and is maintained at +2000 volts either by utilizing the electrode 17 orby using a nozzle made of conducting material and connecting the voltagesource to the nozzle. The platen 11 is constantly maintained atapproximately 5000 volts and the valving plate 21 is interposed betweenthe nozzle 13 and the platen 11. The valving plate 21 has an aperture 22formed in it which is of the order of .015 inch in diameter and the jet12 is directed from the nozzle 13 toward the platen 11 through thisaperture. The valving plate 21 is connected to a suitable voltage sourcethrough a control device 23 which may be operated to maintain the plate21 at either ground potential or at +500 volts. When the valving plate21 is maintained at ground potential, the jet 12 will be directedthrough it and will be accelerated by it, toward the platen 11. When thecontrol device 23 is operated to change the voltage of the plate 21 fromground potential to +500 volts, this change in the potential differencebetween the nozzle 13 and the valving plate 21 will be sufficient tointerrupt the flow of ink from the nozzle 13 and cause the meniscus atthe nozzle to return to the configuration as illustrated at 16 in FIG.2. Thus the valving plate 21 serves as a means for turning the jet 12 onand off and may be controlled by the control device 23 in any suitablemanner to determine the duration of the jet. Consequently, if the tapeis drawn past the platen 11 as shown in FIG. 3 at a constant known rate,the apparatus as shown in FIG. 3 will effect the same result asdescribed in connection with the apparatus of FIG. 1.

It "has been found that if a relatively large plate 2.1 is used, with anaperture of the size specified hereinbefore, the tendency of the jet toform into a spray is inhibited to such an extent that the jet may bemaintained at a uniform size when projected over an appreciabledistance. For example, with the voltages mentioned herein, in connectionwith the apparatus shown in FIG. 3, a jet has been projected for adistance of over .250 inch without appreciably enlarging and at thepoint of its impingement on the paper, produced a line .002 inch W1 e.

In FIG. 4 there is illustrated an embodiment of the invention whereinthe jet 12 is directed from the nozzle 13 onto the tape 10 in front ofthe platen 11 and is con trolled by a pair of electrodes or plates 31and 33 having apertures 32 and 34 in them, respectively. The electrodeor plate 31 serves as a jet forming electrode whereas the plate 33serves as a valving or shut-off electrode. The aperture 32 in the plate31 was .015 inch in diameter and the aperture 34 in plate 33 was .040inch in diameter. In this embodiment of the invention, the plate 31 waspositioned .035 inch from the end of the nozzle 13, the plate 33 waslocated .045 inch from the plate 31 and the platen 11 was .200 inch fromthe plate 33. With this arrangement, it was found that if a positivepotential of +3500 volts were applied to the nozzle 13, a positivepotential of +1500 volts were applied to the accelerating electrode 31,ground potential were applied to the valving plate 33 and a negativepotential of -5000 volts were applied to the platen 11, a jet of inkwould be directed from the nozzle through the apertures 32 and 34 in theplates 31 and 33, respectively, onto the paper 10 in front of theelectrode 11. When the potential of the valving or shut-off plate 33 wasraised from ground potential to a positive potential of +2500 volts, thejet 12, after passing through the aperture 32 in the plate 31, would bedirected back to the plate 31 and would then drop off the plate 31. Withthe arrangement shown in FIG. 4, it will thus be apparent that a jet ofink may be directed to the tape 10 under control of the valving plate33. When the potential of the valving plate 33 is raised toapproximately +2500 volts, the jet of ink will be directed back againstthe surface of the plate 31 substantially as indicated by the dottedlines at 35 and with this arrangement, it is possible to get a fasterresponse than with the previously described embodiments of theapparatus, by varying the voltage of the valving plate or electrode 33,since the stream of ink from the nozzle 13 is never stopped but ratheris diverted by the valving plate or electrode 33 away from the paper 10.

In FIG. 5, there is illustrated an embodiment of the invention whereinthe beam or jet of ink 12 which is projected from the nozzle 13 isdirected through an aperture 40, in a valving plate 41, in its pathtoward the platen 11. The jet or ray of ink 12, after passing throughthe aperature 40 is directed between a pair of vertical deflectionelectrodes 42 and 43 and thence between a pair of horizontal deflectingelectrodes 44 and 45. The electrodes 42, 43, 44 and 45 serve to guidethe jet 12 somewhat in the manner that the deflecting electrodes of acathode ray tube deflect the electron beam therein.

In the apparatus shown in FIG. 5, there is embodied the structure toprovide for generating an ink jet and using it for the printing ofcharacter images. In this embodiment of the invention, the reservoir 15would prefer-ably be positioned approximately 6 inches above the nozzle13 in order to provide the proper meniscus 16 at the orifice of thenozzle, as is true in all the other embodiments of the inventiondiscussed hereinbefore. In one embodiment of the structure thus brieflydescribed, it has been found that with a nozzle having an insidediameter of .005 inch, and an outside diameter of .010 inch located .035inch away from the plate 41, the aperture 40 in the plate 41 being .015inch in diameter and the exit orifice of the nozzle 13 being .280 inchfrom the platen 11 and the thickness of the plate 41 being .004 inch, asuitable jet 12 may be generated and directed from the nozzle to thetape or web of paper 10. In this embodiment of the invention, the nozzlevoltage has been found to be effective if it is maintained at +4000volts with the plate 41 at a potential of +2000 volts and the platen 11potential at -3000 volts. With this arrangement, the jet may be turnedoff by raising the voltage of the plate 41 from +2000 volts to +2500volts positive so that the potential difference between the nozzle 13and the plate 41 is reduced from 2000 volts to 1500 volts. This shift inpotential difference will turn the jet on or ofl. The deflectingelectrodes 42, 43, 44 and 45 comprise two pairs of fine wires, but mightwell be plates, spaced about .015 inch to either side of the axis of thejet 12. The pair of electrodes 42 and 43 were located approximately .040inch from the plate 41 and the second pair, that is, the pair ofelectrodes which effects the horizontal deflection and are designated 44and 45, were spaced .040 inch from the first pair. The verticaldeflection electrodes 42 and 43 were maintained at a level of about 1200volts positive while the horizontal deflection electrodes 44 and 45 weremaintained at a level of about 400 volts positive. These levels are suchas to keep an approximately constant potential gradient between theplate 41 and the platen 11. Deflection of the jet 12 may be produced byraising the potential of one electrode of a pair of electrodes whilelowering the potential on the other electrode. A potential difference of500 volts between the members of either the pair 42 and 43 or the pair44 and 45 will produce a deflection of about .070 inch at the platen 11.

It should be borne in mind that the voltages and dimensions given inconnection with the description of FIG. 5 and also FIGS. 1, 3 and 4 aremore or less dependent upon the characteristics of the ink being used.especially its viscosity, surface tension, and conductivity. The ClearPrint ink described hereinbefore has been found to be satisfactory andto be usable with the mechanisms described hereinbefore. It should beunderstood, however, that the specific examples given hereinbefore,particularly the dimensional examples, may be varied over a relativelywide range, and that the examples given are simply illustrative.

In using the apparatus disclosed in FIG. 5, the tape 10 may be steppedintermittently, and each time it comes to rest, a character may beformed on the tape by deflecting the jet 12 under control of theelectrodes 42 to 45 and turning the jet on and off by means of the plate41. This result may be efiected in a number of ways, for example, theink spot can be made to sweep the character area several times in avertical direction, and to he stepped horizontally during each retrace,forming a line raster covering the character image. During each scanningoperation of the jet 112, the jet may be turned on when a dark portionof the image is to be recorded and oh when a background portion is to berecorded.

Although several specific embodiments of the invention have beendescribed hereinbefore, it should be understood that numerous variationsthereof may be employed without departing from the invention, and it isreiterated that the examples given of voltages and dimensions are simplyillustrative of methods and apparatus which may be employed.

What is claimed is:

1. The method of directing a jet of ink from a nozzle and attracting itonto a recording medium mounted on a platen spaced from said nozzlewhich comprises (a) supplying ink to said nozzle at a hydrostaticpressure such that a supply of ink will form a meniscus at the nozzlewithout running or dripping from it,

(b) positioning a metallic plate in spaced relation to and opposite theexit orifice of the nozzle,

() applying a potential difference between the plate and the nozzlewhich difference is proportional to the distance between the plate andthe nozzle in the range of approximately 1800 to approximately 2200volts at distances between approximately .035" and .045 to generate ajet of ink in a single file of droplets,

(d) positioning a recording medium in the path of the jet of ink, and

(e) maintaining a potential difference between the nozzle and platen toattract a jet of ink to the recording medium.

2. The method of directing a jet of ink from a nozzle and attracting itonto a recording medium mounted on a platen spaced from said nozzlewhich comprises (a) supplying ink to said nozzle at a hydrostaticpressure such that a supply of ink will be maintained at the nozzle anda meniscus of ink will form that will not flow from the nozzle, and

(b) applying a potential to the ink at the nozzle which potential isfrom 1800 to 2200 volts different from that applied to the platen whenthe platen is spaced from the nozzle a distance of between .035" and.045" to draw a jet of ink from the nozzle to the recording medium.

3. The method of directing a jet of ink from a nozzle and attracting itonto a recording medium mounted on a platen spaced from said nozzlewhich comprises (a) supplying ink to said nozzle at a hydrostaticpressure such that a meniscus of ink will form at the nozzle but willnot flow from the nozzle,

(b) applying a potential difference between the nozzle and platen whichis proportional to the distance between them in the range from 1800 to2200 volts at a distance between .035" and .045" to attract the jettoward platen and onto the recording medium, and

(c) raising the potential diflerence between the platen and the nozzleto approximately 2500 volts to interrupt the flow of ink from the nozzletoward the platen.

4. An apparatus for directing a jet of ink onto a recording medium whichcomprises (a) a nozzle, (b) means for supplying ink to said nozzle at apres- '8 sure that maintains a bulging meniscus at the exit of thenozzle,

(0) a plate spaced approximately .035" to .045 from the the exit of thenozzle,

(11) means for applying a potential between the exit of the nozzle andthe plate in the range of approximately 1800 to 2200 volts to generate ajet of ink in a single file of droplets,

(e) said plate having an aperture through which the jet is directed,

(f) a platen in line with and spaced beyond the nozzle and plate forsupporting a recording medium, (g) said platen being spaced .200" to.280" from the plate,

(It) means for applying a potential of 7000 volts to 8000 volts betweenthe platen and the nozzle to attract the file of droplets onto saidrecording medium.

5. An apparatus for directing a jet of ink onto a recording mediumcomprising (a) a nozzle,

(b) means for maintaining a supply of ink at the exit orifice of saidnozzle,

(0) a platen spaced approximately .250" to .280" from said nozzle forsupporting a recording medium in position opposite the nozzle,

(d) a control electrode spaced .035 to .045" from said nozzle,

(e) means for applying a potential difference between the nozzle and theplaten of from 7000 to 8500 volts to attract the ink toward the platenand onto the recording medium,

(f) means for applying a potential to the control plate which is withinthe gradient from the nozzle to the platen and which is from 1500 to2000 volts different from the nozzle to generate a jet of ink and directit toward the platen, and

(g) means for applying a potential which is 2500 volts different fromthe potential of the nozzle in the said gradient to stop the flow of inkfrom the nozzle.

6. An apparatus for directing a jet of a marking me dium from a nozzleand attracting it onto a recording medium comprising (a) a nozzle,

(b) a platen mounted in spaced relation to and opposite the exit orificeof the nozzle for supporting a supply of recording medium in the path ofa jet of marking medium drawn from the nozzle,

(c) means for maintaining said nozzle at from +3500 to +4000 voltspotential,

(d) means for maintaining said platen at from +5000 to +3000 voltspotential to attract the marking medium to the recording medium, saidplaten being positioned approximately .280" from said nozzle,

(e) an accelerating electrode spaced approximately .035 from said nozzleand having an aperture in alignment with a jet of marking medium drawnfrom the orifice of the nozzle.

(7) means for maintaining said accelerating electrode at approximately+1500 volts,

(g) a valving electrode between the platen and the acceleratingelectrode and spaced approximately .045" from the acceleratingelectrode, and

(h) means operable to maintain the valving electrode at zero potentialto sustain the jet of marking medium and direct it toward the paten andto shift the potential of the valving electrode to +2500 volts to directthe jet of marking medium back onto the surface of the acceleratingelectrode closest to the platen.

medium comprising (a) a nozzle,

(b) a platen mounted in spaced relation to and 0p posite the exitorifice of the nozzle for supporting a supply of recording medium in thepath of a jet of marking medium drawn from the nozzle,

(0) means for maintaining said nozzle at a potential of approximately+4000 volts,

(d) means for maintaining said platen at a potential of approximately-3000 volts,

(e) an accelerating electrode spaced approximately .035" from saidnozzle and having an aperture in alignment with a jet of marking mediumdrawn from the orifice of the nozzle,

( means for maintaining said accelerating electrode at a potential ofapproximately +2000 volts to direct said jet of marking medium towardssaid platen,

(g) means for changing the potential of said accelerating electrode toapproximately +2500 volts to stop said jet of marking medium from comingfrom the nozzle,

(h) two pairs of deflecting electrodes interposed between theaccelerating electrode and the recording medium, one of said pairs beingspaced from the accelerating electrode a distance of approximately .040"and both electrodes of said one pair being maintained at approximately+1200 volts, the other of said pairs being spaced .040" from said onepair, both of said electrodes of said other pair being maintained atapproximately +400 volts,

(i) and means for varying the potential of the deflecting electrodes byraising the voltage of one electrode of a pair while lowering thevoltage of the voltage of the other electrode of the same pair todeflect the jet.

References Cited in the file of this patent UNITED STATES PATENTS1,941,001 Hansell Dec. 28, 1933 2,143,376 Hansell Ian. 10, 19392,512,743 Hansell June 27, 1950 2,600,129 Richards June 10, 19522,676,868 Jacob Apr. 27, 1954 2,869,510 Renner Jan. 20, 1959 2,894,799McCreary July 14, 1959 2,925,312 Hollmann Feb. 16, 1960 FOREIGN PATENTS24,397 Australia Mar. 27, 1931 1,027,113 Germany Mar. 27, 1958 TENTOFFICE CERTIFICATE OF CORRECTION Patent N00 3,060,429 October 23, 1962Charles R, Winston It is hereby certified that error appears in theabove numbered patent requiring correction and that the said LettersPatent should read as corrected below.

Column 1 line 51 for product" read produce column 2, line 5, for "its"read it line 15, after sheet" insert which column 3, line 16, for"aanlogous" read analogous "3 column 4, line 59, after "instant", firstoccurrence, insert th column 6, line 12, for "aperature" read aperturecolumn 8, line 67, for "paten" read platen column 10, line 9, strike out"voltage of the;

ERNEST w. SWIDER v DAVID A Attesting Officer Commissioner of PatentsUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,3,060,429 October 23, 1962 Charles R, Winston It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 1, line 51, for "product" read produce column 2, line 5, for"its" read it line 15, after "sheet" insert which column 3, line 16, for"aanlogous" read analogous column 4, line 59, after "instant", firstoccurrence, insert th column 6, line 12, for

aperature" read aperture column 8, line 67, for "paten" read M platencolumn 10, line 9, strike out "voltage of the";

Signed and sealed this 3rd day of September 1963.,

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents

